In a conditional access system a broadcast service, e.g. a television program or movie, is typically broadcasted to a client device in an encrypted format. Control words required for decrypting the encrypted broadcast service are transmitted from a head-end system to a secure client module connected to the client device regularly in entitlement control messages (ECMs). For increased security, the ECMs are encrypted with an ECM key that is made available by the head-end system to the secure client module when authorized, e.g. when the client has a subscription to the broadcast service. The ECM key is transmitted from the head-end system to the authorized secure client module in an entitlement management message (EMM). The EMM is usually also encrypted and decryptable with an EMM key hardcoded into the secure client module.
The client device and secure client module provide decryption of the encrypted broadcast service, enabling an end-user device to display or record the decrypted broadcast service. A set-top box is a known example of a client device. A smartcard inserted into the set-top box functions as secure client module. A television set or video recorder as end-user device can e.g. be used to display or record a decrypted television program of movie.
The client device, secure client module and end-user device can be integrated into a single end-user device. Examples of a single end-user device are a mobile phone, a smartphone, a computer, a notebook and a PDA.
Usage of an encrypted broadcast service is typically monitored by a vendor specific monitoring module in the client device. The monitoring module captures requests from the end-user for a broadcast service to generate a usage report for the broadcast service. Requests are e.g. made by using a remote control on the client device and by choosing services from an electronic service guide presented to the end-user on the end-user device. For deriving the status of the broadcast service, vendor specific triggers, as implemented by the vendor in the client device, are used.
There is a need in the art for a non-vendor specific solution of monitoring usage of encrypted broadcast services.